+str - Renames SynchronousPublisherFromIterable to SynchronousIterablePublisher
       Introduces AsynchronousIterablePublisher
       Gives names to most of the publishers
Merge branch 'wip-misc-materializer-improvements-√' of github.com:akka/akka into wip-misc-materializer-improvements-√

Conflicts:
	akka-stream/src/main/scala/akka/stream/impl/SynchronousIterablePublisher.scala
	akka-stream/src/main/scala/akka/stream/scaladsl/ActorFlowSource.scala